3.4V Zener Diode

DZ3.4

Zener diodes differ from regular diodes in that they have a varying "reverse-breakdown" voltage. That means you apply voltage across them, and when a preset voltage is reached, they start conducting. A common analogy is a "pressure relief valve". They have lots of uses, especially in safety circuits where you want to make sure a voltage signal doesn't exceed a limit that might damage the circuit.

This 1N4728A zener diode is set at 3.4V, making it ideal for protecting the inputs of a 3.3V circuit. specifically, it has a minimum voltage of 3.315 V and a maximum voltage of 3.465 V, a leakage current of 1 V and a test current of 76 mA.